JP2003202262A - Optical monitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an optical monitor of wide band capable of reducing the number of components and free form the dependency on wavelength. <P>SOLUTION: The light from an optical fiber 21 is entered into a dot mirror 30 through a collimated lens 22. The dot mirror is a reflection plate on which small openings are uniformly formed, and the transmitted light is monitored by a photodetector 25. The reflected light is returned to a fiber 24 for emission to be used for main purpose. Whereby the optical monitor free from the dependency on wavelength can be realized. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical monitor suitable for an optical signal having a broadband wavelength characteristic.

[0002]

2. Description of the Related Art A monitor having an optical branching function is used to branch a part of an optical signal of an optical fiber and detect its intensity. FIG. 4 is a schematic diagram showing the configuration of an optical monitor having an optical branching function. In this figure, an optical fiber 11 is an optical fiber through which an optical signal whose optical intensity is to be measured is guided, and a fiber coupler 12 is a device in which two optical fibers are fused and a part of optical power is branched. Is. Then, the optical fiber 13 for monitoring and the optical fiber 14 for transmission are taken out from the fiber coupler 12. An optical connector 15, a collimator lens 16 and a photo detector 17 are fixed to a holder 18 at the monitor port as shown in the figure. By monitoring an optical signal from the monitor port obtained by the photo detector 17, an optical fiber is obtained. The optical power of 11 can be detected.

FIG. 5 is a diagram showing the structure of another conventional optical monitor. As shown in this figure, the fiber for incidence 2
1. The collimator lens 22 is made to enter the dielectric mirror 23 with a slight inclination from the vertical surface of the dielectric mirror. Then, the emitting fiber 24 is provided at a position where the reflected light can be received. The dielectric mirror 23 is a half mirror that transmits a part of incident light and reflects a part of the incident light by using a dielectric multilayer film. The light transmitted through the dielectric mirror 23 is converted into an electric signal by the photodetector 25, amplified by the light receiving circuit, and displayed on the display 7. This way the incident fiber 2
A part of the light from 1 is obtained as the monitor light, and the level of the incident light can be detected.

[0004]

In the optical monitor using the fused fiber coupler, the wavelength dependence of the branching ratio is relatively small, but this method has a problem that the number of parts is large and the mounting area is large. was there. Further, the optical monitor using the dielectric multilayer film mirror has a drawback that it is difficult to accurately monitor the level of a broadband optical signal because it depends on the wavelength. For example, in the 1.3 μm band and the 1.55 μm band, it was difficult in design to make the light branching ratios equal.

The present invention has been made in view of the above conventional problems, and provides an optical monitor having a simple structure capable of accurately obtaining a branching ratio of light corresponding to a wavelength of a wide band. The purpose is to

[0006]

According to a first aspect of the invention of the present application, a dot mirror having a reflecting surface in which a minute opening is uniformly formed in a light incident area, and light is incident on the dot mirror. An incident part, a light receiving part for receiving one light branched by the dot mirror, and an emitting part for receiving the other light of the light branched by the dot mirror. Is.

According to a second aspect of the present invention, in the optical monitor according to the first aspect, a collimator lens for collimating the incident light and the emitted light into parallel light is further provided between the incident portion and the emission portion and the dot mirror. Then, the incident part is an optical fiber for incidence in which a light emitting end face is arranged at a focal position of the collimator lens, and the emitting part is reflected by the dot mirror and condensed by the collimator lens. It is characterized in that it is an optical fiber for emitting reflected light.

[0008]

1 is a diagram showing a first embodiment of an optical monitor according to the present invention. The same parts as those in the conventional example are designated by the same reference numerals and detailed description thereof will be omitted. As shown in the figure, it has an incident optical fiber 21 and a collimator lens 22 for converting this light into parallel light, and an outgoing optical fiber 24 is provided on the outgoing side. Now, in this embodiment,
A dot mirror 30 is used instead of the above-mentioned dielectric mirror. As shown in FIG. 2, the dot mirror 30 is a square flat plate, and a metal plate such as gold is used. The surface is a total reflection part. The dot mirror 30 has minute openings formed at predetermined intervals or at random as shown in the figure. This opening is formed uniformly in at least all the areas where light enters. The broken line in the figure shows the range of the incident light which becomes a parallel beam by the collimator lens 22 and is incident on the dot mirror 30.
Then, of the light that has entered the dot mirror 30, the light that has entered the minute apertures directly passes through the dot mirror 30 and enters the photodetector 25. Photo detector 2
A light receiving circuit 26 such as an amplifier and a display 27 are connected to 5. Further, the light incident on the total reflection portion other than the opening portion is reflected by the surface thereof and is reflected by the optical fiber for emission through the collimator lens 22. Therefore, the optical signal can be monitored with a constant branching ratio regardless of the wavelength of light.

The branching ratio of the dot mirror 30 is
Different dot mirrors 30A and 3 shown in FIGS.
As shown in the example of 0B, it can be arbitrarily selected by changing the density of minute openings.

Next, a second embodiment of the present invention will be described with reference to FIG. The optical fiber 31 is an optical fiber through which an optical signal whose light intensity is to be measured is guided, and is connected to the two-core capillary 32 as illustrated. The two-core capillary 32 is a cylindrical member that holds the optical fiber 31 and the outgoing optical fiber 33, and the right end thereof has the optical fiber 3
The output end faces 1 and 33 are held at substantially symmetrical positions. The right end is cut with a slight tilt from the central axis so that the reflected light does not return to the incident side. The 2-core capillary 32 is a cylindrical refractive index distribution lens (Graded Index Lens, GR hereinafter) having the same diameter as the 2-core capillary 32.
It is attached to an IN lens) 34. GRIN
The lens 34 is a lens configured so that the refractive index continuously increases from the periphery toward the central axis, and the light emitted from the optical fiber 31 can be made into parallel light by selecting the length thereof. it can. The left end portion of the GRIN lens 34 is processed so that the surface in contact with the two-core capillary 32 is inclined and has a series of cylindrical shapes together with the two-core capillary 32. The dot mirror 35 is attached to the lower end of the GRIN lens 34. The dot mirror 35 reflects incident light at a predetermined ratio and transmits a part thereof, and is the same as the dot mirror 30 described above.
The photodetector 25 is arranged at a position where the light emitted through the dot mirror 35 can be received. The photodetector 25 is connected to the light receiving circuit 26, and the light receiving circuit 26 is connected to the display 27. Here, the photodetector 25, the light receiving circuit 26, and the display 27 have a light receiving portion for receiving one of the branched lights.

Also in this embodiment, when light enters from the optical fiber 31, a part of the light passes through the dot mirror 35. The light amount level that has passed is detected by the display 27.
On the other hand, the light reflected by the dot mirror 35 enters the outgoing optical fiber 33 and is used for its original purpose. Therefore, the intensity of the light incident from the optical fiber 31 is determined by the photodetector 2
It is possible to detect based on the light receiving level of 6. Also in this case, the branching ratio is determined by the number of openings of the dot mirror 35, the area thereof, and the area of the total reflection portion.

In each of the above-mentioned embodiments, the optical fiber 21 or 31 is used as the incident part, but a laser light source or the like can be directly used as the incident part. Further, since the dot mirror branches by transmitting and reflecting light, it is possible to provide a light receiving portion for monitoring on the reflection side and use the transmitted light for the main purpose.

[0013]

As described in detail above, according to the present invention, since the dot mirror having a minute and uniform aperture is used for branching the light, a constant branching ratio can be obtained in a wide band wavelength. . Further, since the structure of this dot mirror is simple, it is possible to realize an optical monitor module which is excellent in productivity, low in cost, excellent in reliability and miniaturized.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an optical monitor according to a first embodiment of the present invention.

FIG. 2A and FIG. 2B are front views showing different examples of dot mirrors.

FIG. 3 is a schematic diagram showing a configuration of an optical monitor according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing an example of a conventional wide-band compatible optical monitor.

FIG. 5 is a schematic diagram showing the configuration of another conventional optical monitor.

[Explanation of symbols]

11,13,14,21,24 Optical fiber 22 Collimating lens 25 photo detector 26 Light receiving circuit 27 Display 30,35 dot mirror 32 2-core capillary 34 GRIN lens

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naoyuki Shikada             5823 Tonokamisaka, Komaki City, Aichi Prefecture             Suntec Photonics Laboratory Co., Ltd.             Within F term (reference) 2G065 AA04 AB02 BB02 BB11                 2H037 AA01 BA11 CA38 DA03 DA04                       DA06

Claims (2)

[Claims] 1. A dot mirror having a reflecting surface in which a minute opening is uniformly formed in a region where light is incident, an incident portion for injecting light to the dot mirror, and one of the ones branched by the dot mirror. An optical monitor comprising: a light receiving section for receiving light; and an emitting section for receiving the other light of the light branched by the dot mirror. 2. A collimator lens for collimating incident light and emitted light into parallel light is further provided between the incident portion and the emitted portion and the dot mirror, and the incident portion has a light emitting end face of the collimator lens. Is an optical fiber for incidence arranged at the focal position of, and the emission part is an optical fiber for emission on which the reflected light reflected by the dot mirror and condensed by the collimator lens is incident. The optical monitor according to claim 1, which is characterized in that.